Apparatus and method for assigning sub-channels in an OFDMA system

Abstract

A sub-channel assignment apparatus and method of minimizing interference caused by sub-channel frequency overlaps when assigning sub-channels for sectors of a base station in an OFDMA system of a FDMA type. The apparatus includes: a plurality of sector channel management parts that assign at least one channel having assignable channel indexes in response to requests from users in a sector managed by the sector channel management part, and report sector load information regarding the total number of the requests from the users in the sector; and a channel assignment scheduler for using the sector load information reported from each channel management part to calculate the number of assignable channels per class for each of the sectors, and determines the assignable channel indexes per class for each of the sectors according to the number of assignable channels, and forwards the assignable channel indexes to each of the sector channel management parts.

Description

[0001] This Non-Provisional Application claims priority under 35 U.S.C. § 119(a) to Korean Patent Application No. 10-2005-0095938 filed in Korea on Oct. 12, 2005. Which is hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to an OFDMA (Orthogonal Frequency Division Multiplexing Access) system, and more particularly to an apparatus and method for minimizing interference caused by sub-channel frequency overlaps when assigning sub-channels for sectors of a base station in an OFDMA system of a FDMA (Frequency Division Multiple Access) type. [0004] 2. Background of the Related Art [0005] Recent advances in mobile communication technologies have led to a move from using analog methods to digital methods in signal processing. Also, in addition to voice and text communication services, multimedia communication services are now also provided for commercial use. In line with such progress, there has been a growin...

AI Technical Summary

Benefits of technology

[0013] Embodiments according to the present invention also provide an OFDMA system that performs sub-channel assignment at a base station or controller such that no sub-channel is multiply assigned to the neighboring sectors when the cell load of the system is low, and such that interference effects caused by the frequency overlap of the sub-carriers are minimized when the cell load is above a critical point where the assignment of the sub-carriers of the same frequency to the multiple sectors or cells is needed.

[0014] Embodiments according to the present invention further provide an OFDMA system with a base station or controller that provides faster channel assignment scheduling and maximum utilization efficiency of the radio resource by using a quantitative value on the ratios for assigning the sub-channels for each sector, wherein the ratios are based on the channel and load information of each sector.

Problems solved by technology

Further, since the same medium (channel) is shared by a plurality of users, the interference from neighboring cells or sectors greatly affects the communication quality.

However, this inevitably leads to the interference phenomenon caused by the sub-carrier frequency overlap when there is an increase in the number of users in the multiple-sector environment.

However, conventionally, the assignment of the combined sub-channels is not managed by a single base station or controller, but rather independently by each sector, such that the problem of the interference caused by frequency overlap (i.e., sub-carrier overlap) arises.

Thus, the interference phenomenon caused by the frequency overlap cannot be efficiently managed.

Images